[Python] Converting xml.etree.ElementTree to string raises "TypeError: argument of type 'int'...

I have a simple XML element created with xml.etree.ElementTree in Python 3.

import xml.etree.ElementTree as ElementTree
person = ElementTree.Element("Person", Name="John", Age=18)


I can use Element.get() to access individual attributes from my element without any issues.

name = person.get("Name")
age = person.get("Age")
print(name + " is " + str(age) + " years old.")
# output: "John is 18 years old"


However, if I try to convert my element to a string with .tostring(), I get an error "TypeError: argument of type 'int' is not iterable".

print(ElementTree.tostring(person)) # TypeError


Why can't I use .tostring() on an xml.etree.ElementTree.Element with an integer attribute?


Full code:

import xml.etree.ElementTree as ElementTree

person = ElementTree.Element("Person", Name="John", Age=18)
print(ElementTree.tostring(person)) # TypeError


Full traceback:

Traceback (most recent call last):
File "C:\Users\svascellar\AppData\Local\Programs\Python\Python36-32\lib\xml\etree\ElementTree.py", line 1079, in _escape_attrib
if "&" in text:
TypeError: argument of type 'int' is not iterable

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "C:/Users/svascellar/.PyCharmCE2017.3/config/scratches/scratch_13.py", line 3, in <module>
print(ElementTree.tostring(person))
File "C:\Users\svascellar\AppData\Local\Programs\Python\Python36-32\lib\xml\etree\ElementTree.py", line 1135, in tostring
short_empty_elements=short_empty_elements)
File "C:\Users\svascellar\AppData\Local\Programs\Python\Python36-32\lib\xml\etree\ElementTree.py", line 776, in write
short_empty_elements=short_empty_elements)
File "C:\Users\svascellar\AppData\Local\Programs\Python\Python36-32\lib\xml\etree\ElementTree.py", line 933, in _serialize_xml
v = _escape_attrib(v)
File "C:\Users\svascellar\AppData\Local\Programs\Python\Python36-32\lib\xml\etree\ElementTree.py", line 1102, in _escape_attrib
_raise_serialization_error(text)
File "C:\Users\svascellar\AppData\Local\Programs\Python\Python36-32\lib\xml\etree\ElementTree.py", line 1057, in _raise_serialization_error
"cannot serialize %r (type %s)" % (text, type(text).__name__)
TypeError: cannot serialize 18 (type int)

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